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Earth and Space Sciences · 术语表

什么是 Isochron?

Definition 25.3 High School Earth and Space Sciences · 第 25 章 — Radiometric Dating and the Age of the Earth

An isochron is the straight line on which lie the points of minerals or rocks that formed at the same time from the same source and have stayed closed systems since, when the ratio of daughter to stable isotope is plotted against the ratio of parent to stable isotope. Its slope gives their age, and the point where it meets the vertical axis gives their starting ratio.

The rubidium–strontium isochron of the Varden granite (exercise data). When the granite formed, all its minerals lay on the dotted horizontal line; since then each has risen in proportion to its rubidium, and they now lie on the solid line.
The rubidium–strontium isochron of the Varden granite (exercise data). When the granite formed, all its minerals lay on the dotted horizontal line; since then each has risen in proportion to its rubidium, and they now lie on the solid line.
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